Calculation of increased soil shear strength from desert plant roots

Abstract

Tarim River is one of the most important water sources in western China, which experiences serious soil erosion. Desert plant roots of various species in the Tarim River Basin can effectively stabilize the slopes. In this study, a total of 28 soil samples were obtained including 17 samples of root-soil composites. The results of soil tests indicate that the cohesion of root-soil composites with values from 9.43 to 28.30 kPa is generally higher than that of no-root soils with values from 3.14 to 16.51 kPa. However, the roots have a minimal impact on the internal friction angle of soils. The results of single root tensile experiment indicate that the tensile strengths of root decrease with the increase of root diameter, while the tensile forces increase with it. Two models of the root and soil interaction were proposed based on the assumptions of roots rigid state and flexible state, which represent the increased maximum and minimum shear strengths, respectively. The calculated value of increased maximum and minimum shear strengths compared with the experimental results proved that the measured increased shear strengths were within the theoretical calculation range, which could provide a theoretical calculation method for evaluating the effects of desert plant roots on riverbank soil shear strength.